1. Field of the Invention
The present invention relates to an ink sheet cartridge, and more particularly, it relates to an ink sheet cartridge mounted on a printer.
2. Description of the Background Art
An ink sheet cartridge mounted on a printer is known in general. For example, Japanese Patent Laying-Open Nos. 9-136464 (1997), 6-246995 (1994), 9-323456 (1997) and 2005-47054 disclose such ink sheet cartridges.
The aforementioned Japanese Patent Laying-Open No. 9-136464 discloses an ink ribbon cartridge (ink sheet cartridge) including a shell (bobbin case) having a spool storage portion rotatably storing a ribbon feed spool (feed bobbin) wound with an ink ribbon and a ribbon take-up spool (take-up bobbin) taking up a spent ink ribbon, in which the shell is constituted of a shell body having the spool storage portion and a lid while the lid is openable/closable with a hinge integrally formed on the shell body. In this ink ribbon cartridge, an engaging pawl of an engaging section provided on the lid and an engaging hole provided on the shell body engage with each other, thereby fixing the lid in a closed state. The hinge, integrally formed on the shell body, is provided with a protrusion. In this ink ribbon cartridge according to Japanese Patent Laying-Open No. 9-136464, it is possible to recycle the shell (bobbin case) by opening the lid after using the ink ribbon, exchanging the spool and thereafter closing the lid again.
The aforementioned Japanese Patent Laying-Open No. 6-246995 discloses an ink ribbon cartridge (ink sheet cartridge) including a shell (bobbin case) having a spool storage portion rotatably storing a ribbon feed spool (feed bobbin) wound with an ink ribbon and a ribbon take-up spool (take-up bobbin) taking up a spent ink ribbon, in which the shell is constituted of a shell body having the spool storage portion and a lid separated from the shell body while the lid and the shell body are combined with each other for rendering the lid openable/closable. In this ink ribbon cartridge, an engaging pawl of an engaging section provided on the lid and an engaging hole provided on the shell body engage with each other, thereby fixing the lid in a closed state. The hinge is in a protruding state for fixing the lid in the openable/closable manner. In the ink ribbon cartridge according to Japanese Patent Laying-Open No. 6-246995, it is possible to recycle the shell by opening the lid after using the ink ribbon, exchanging the spool and thereafter closing the lid again, similarly to the aforementioned ink ribbon cartridge according to Japanese Patent Laying-Open No. 9-136464.
The aforementioned Japanese Patent Laying-Open No. 9-323456 discloses a cassette case (bobbin case) formed by an upper cassette (upper component) and a lower cassette (lower component) rotatably storing a feed bobbin delivering a sheet and a take-p bobbin taking up the sheet respectively, in which two slidable fasteners are mounted on a coupling portion of the upper cassette coupling the upper and lower cassettes with each other so that the upper and lower cassettes are fixable. The upper and lower cassettes of this cassette case can be separated from each other by sliding the fasteners. Further, it is possible to recycle the body of this cassette case by exchanging spent feed and take-up bobbins and thereafter fixing the upper and lower cassettes to each other again.
The aforementioned Japanese Patent Laying-Open No. 2005-47054 discloses a thermal transfer sheet cassette (ink sheet cartridge) storing a sheet body formed by a take-up core (take-up bobbin), a feed core (fed bobbin) and a thermal transfer sheet (ink sheet), on which lid bodies and a core holder can be easily mounted by engaging concave rails provided in the core holder and protrusions provided on the lid bodies with each other thereby guiding the protrusions provided on the lid bodies along the concave rails. This thermal transfer sheet cassette has the core holder rotatably storing the take-up core and the feed core and the two lid bodies covering the core holder.
An ink sheet cartridge applied to a thermal transfer printer is also known in general. The structure of a conventional ink sheet cartridge 100 is described with reference to FIGS. 16 to 23.
As shown in FIG. 16, the conventional ink sheet cartridge 100 comprises a resin upper component 102 and a resin lower component 103 constituting a bobbin case 101, a fed bobbin 104 feeding an ink sheet 106, a take-up bobbin 105 taking up the ink sheet 106 and the ink sheet 106.
The upper component 102 constituting the bobbin case 101 includes a feed bobbin storage portion 102a storing the feed bobbin 104, a take-up bobbin storage portion 102b storing the take-up bobbin 105 and coupling portions 102c and 102d coupling the feed bobbin storage portion 102a and the take-up bobbin storage portion 102b with each other, as shown in FIG. 16. A reinforcing portion 102j for preventing the ink sheet cartridge 100 from twisting resulting from a load applied in printing is provided on the coupling portion 102d of the upper component 102, to extend perpendicularly to the surface of the coupling portion 102d. Feed bobbin holding portions 102e rotatably holding the feed bobbin 104 are provided in the feed bobbin storage portion 102a, while take-up bobbin holding portions 102f rotatably holding the take-up bobbin 105 are provided in the take-up bobbin storage portion 102b. U-shaped engaging portions 102g for fixing the lower component 103 are provided on first end surfaces of the feed bobbin storage portion 102a and the take-up bobbin storage portion 102b of the upper component 102 respectively. Downwardly projecting pawls 102h for fixing the lower component 103 are provided on portions close to second ends of the feed bobbin storage portion 102a and the take-up bobbin storage portion 102b of the upper component 102 respectively. Steps 102i for fixing the lower component 103 are provided on the inner surfaces of the pawls 102h respectively.
Similarly to the upper component 102, the lower component 103 constituting the bobbin case 101 includes a feed bobbin storage portion 103a storing the feed bobbin 104, a take-up bobbin storage portion 103b storing the take-up bobbin 105 and coupling portions 103c and 103d coupling the feed bobbin storage portion 103a and the take-up bobbin storage portion 103b with each other, as shown in FIG. 16. Feed bobbin support portions 103e rotatably supporting the feed bobbin 104 are provided in the feed bobbin storage portion 103a, while take-up bobbin support portions 103f rotatably supporting the take-up bobbin 105 are provided in the take-up bobbin storage portion 103b. Protrusions 103g engaging with the U-shaped engaging portions 102g of the upper component 102 are provided on first end surfaces of the feed bobbin storage portion 103a and the take-up bobbin storage portion 103b of the lower component 103 respectively. Concave receiving portions 103h receiving the pawls 102h of the upper component 102 are provided on portions close to second ends of the feed bobbin storage portion 103a and the take-up bobbin storage portion 103b of the lower component 103 respectively. The concave receiving portions 103h are provided with engaging portions 103i engaging with the steps 102i of the pawls 102h respectively.
The feed bobbin 104 is provided with a sheet feed shaft 104a wound with the ink sheet 106, flanges 104b, a drive shaft 104c, an engaging portion 104d, provided on the drive shaft 104c, having three recess portions engaging with bobbin drive reels of a printer (not shown) and a follower shaft 104e. 
The take-up bobbin 105 is provided with a sheet take-up shaft 105a taking up the ink sheet 106, flanges 105b, a drive shaft 105c, an engaging portion 105d, provided on the drive shaft 105c, having three recess portions engaging with bobbin drive reels of the printer (not shown) and a follower shaft 105e. 
A method of combining the upper and lower components 102 and 103 of the conventional ink sheet cartridge 100 with each other is now described with reference to FIGS. 18 to 23. First, the engaging portions 102g of the upper component 102 are engaged with the protrusions 103g of the lower component 103. Thereafter the pawls 102h of the upper component 102 are moved along arrow A in FIGS. 18, 19, 21 and 22, to be inserted into the concave receiving portions 103h of the lower component 103. Thus, the steps 102i of the pawls 102h provided on the upper component 102 engage with the engaging portions 103i provided on the concave receiving portions 103h of the lower component 103 as shown in FIGS. 20 and 23, thereby fixing the upper and lower components 102 and 103 to each other. At this time, the upper component 102 is hard to bend due to the reinforcing portions 102j provided on the coupling portions 102d of the upper component 102 for preventing the ink sheet cartridge 100 from twisting resulting from a load applied in loading. In order to insert the pawls 102h of the upper component 102 into the receiving portions 103h of the lower component 103, therefore, the lower component 103 is bent along arrow B (inward) shown in FIGS. 19 and 22, thereby inserting the pawls 102h into the receiving portions 103h. In order to separate the upper and lower components 102 and 103 from each other, on the other hand, the pawls 102h of the upper component 102 are outwardly bent for disengaging the pawls 102h from the receiving portions 103h of the lower component 103.
In the conventional ink sheet cartridge 100 shown in FIGS. 16 to 23, however, the lower component 103, which must be inwardly bent when combined with the upper component 102 as described above, may disadvantageously be broken. Further, the upper component 102 is hard to bend due to the reinforcing portions 102j provided on the coupling portions 102d for preventing the ink sheet cartridge 100 from twisting resulting from a load in printing, while the pawls 102h are hard to deflect due to the thickness larger than those of the remaining portions. Thus, it is difficult to disengage the pawls 102h from the receiving portions 103h, and the pawls 102h may disadvantageously be broken due to application of an excessive load when the same are forcibly bent outward to be disengaged from the receiving portions 102h. Therefore, it is difficult to disassemble the bobbin case 101.
In the ink ribbon cartridge (ink sheet cartridge) disclosed in the aforementioned Japanese Patent Laying-Open No. 9-136464, the lid is rendered openable/closable with the hinge integrally formed on the shell body, to result in the protrusion provided on the hinge. Therefore, the outer size of the ink ribbon cartridge is increased due to the protrusion, and components provided in a printer may disadvantageously come into contact with the protrusion.
Also in the ink ribbon cartridge (ink sheet cartridge) disclosed in the aforementioned Japanese Patent Laying-Open No. 6-246995, the lid is rendered openable/closable with the hinge integrally formed on the shell body to result in the protrusion provided on the hinge, similarly to the ink ribbon cartridge disclosed in Japanese Patent Laying-Open No. 9-136464. Therefore, the outer size of the ink ribbon cartridge is increased due to the protrusion, and components provided in a printer may disadvantageously come into contact with the protrusion. Further, the shell body and the lid separated from the shell body are combined with each other through the hinge, and hence it disadvantageously takes time for assembling the hinge.
The cassette case disclosed in the aforementioned Japanese Patent Laying-Open No. 9-323456 disadvantageously requires the two slidable fasteners for fixing the upper and lower cassettes to each other. Therefore, the number of components is disadvantageously increased.
In the thermal transfer sheet cassette disclosed in the aforementioned Japanese Patent Laying-Open No. 2005-47054 constituted of the core holder and the two lid bodies, the number of components as well as the number of assembling steps are disadvantageously increased as compared with a case of covering the core holder with a single lid body.